1. Field of the Invention
The present invention relates to a radiation imaging apparatus, a system and a method as well as a program preferable for use in medical diagnosis and industrial non-destructive inspection. As described herein, a radiation is intended to include electromagnetic waves such as X-rays and γ-rays, α-rays, and β-rays.
2. Description of the Related Art
Conventionally, an X-ray imaging system installed in a hospital and the like is divided into an analog system that irradiates a patient with an X-ray and irradiates film with the X-ray having penetrated a patient and a digital system that irradiates a patient with X-ray and converts an X-ray having penetrated a patient into an electric signal and accumulates it.
In FIG. 16, reference numeral 101 denotes an X-ray source of irradiating an X-ray; reference numeral 104 denotes an X-ray generator of generating X-rays outputted from the X-ray source 101; reference numeral 105 denotes a switch (an irradiation button) with which a radiologic technician and the like controls X-ray irradiation by opening and closing operation. Reference numeral 130 denotes an imaging device comprising a CCD imaging element of converting an X-ray having penetrated an object 102 being a patient and the like into an electric signal, an MOS imaging element or an imaging element in use of amorphous silicon, and the like. Reference numeral 103 denotes a phosphor of converting an X-ray having penetrated the object 102 into light such as visible light and the like. Moreover, a controller 140 is provided to control to drive the imaging unit 130 corresponding with a control signal transmitted in accordance with an opening/closing of the switch 105.
The case where the switch 105 is closed at random by the radiologic technician and the like is dealt with as follows in the X-ray imaging system shown in FIG. 16. That is, the control signal is transmitted from the X-ray generator 104 to the controller 140 to synchronize commencement of a drive of the imaging device 130 with an output of the X-ray to carry out temporal coordination.
However, in an X-ray imaging system of a conventional digital system, in order to transmit the control signal from the X-ray generator 104 to the controller 140 for synchronization, connection among them is implemented by wiring. This occasionally worsen imaging efficiency since such wiring is cumbersome and is not so easy to carry at the time of radiographing in case of use as a light and thin imaging device such as a cassette.
In addition, in the case where a manufacture of an X-ray generator is different from a manufacturer of an imaging device, an interface circuit is occasionally required in order to make it possible to transmit and receive the control signal. Moreover, after installation in a hospital, a case of replacing a used X-ray source with the one provided by another manufacturer, a case of repurchasing the X-ray source and the like give rise to problems described below. That is, since an interface occasionally becomes necessary newly in order to make it possible to transmit and receive control signals between the new X-ray source and a controller, it is indispensable to make a lot of interfaces ready for use.
In addition, it seems that a portable, light and thin cassette is convenient to make radiographing easy in space with a limited room inside an ambulance and the like, and a hospital with a narrow radiographing room and the like, for example. On this occasion, X-ray imaging system depriving electric wiring as much as possible deems to be desired.
Therefore, U.S. Pat. No. 6,999,121 discloses a method that makes it possible to radiograph an X-ray image without connecting an X-ray generator to an imaging device with electric wiring. As shown in FIG. 9 of U.S. Pat. No. 6,999,121, in that method, an imaging element transits to an accumulation mode in case of detecting commencement of X-ray irradiation during an idling period (a period from power activation to a panel to commencement of radiographing) required for stabilizing “real read operation” being first read operation of the imaging element. In case of detecting a conclusion of X-ray irradiation, “real read operation” is carried out. In addition, as shown in FIG. 10 of U.S. Pat. No. 6,999,121, X-ray irradiation frequently starts in the midst of “dummy read operation” being second read operation carried out a plurality of times during an idling period. In that case, information in “dummy read operation” after commencement of X-ray irradiation is also used as X-ray image information.